sounds good, it also means we could build H2/O2 engine with no turbopump and no gas generator (the pressure in tank will be even more than enough for the chamber to work, and it will be a gas already), so the engine will be very simple, cheap and reliable. And no long-term storability problem in space, so we can go for the Moon with the H2/O2 engines for the lander instead of the UDMH or MMH. The only problem is that it will be hard to cool the chamber and nozzle as we have no cryogenics on board.

But besides, the density of LOX is over 1000 kg/m3, as the LOX/kerosene pair is almost exactly 1000 kg/m3 while kerosene is lighter than that.

What's the matearials are you talking about (don't say carbon nanotubes ).

Nanotubes (as a practical material) is a distant future thing. I don't expect for anything commercial based on them to appear before 2010, and they will definitely not be available in amount need to build a space vehicle tank until at least 2020 or later. One day i am sure something like this will be built, or at least could be built, but not before 2030 for sure.

I beleive orbital transportation problem will be resolved well before without anything THAT exotic. Say scramjet engine to go to mach 25 is much less exotic at the moment (but still not even remotely possible).

How about carbon fiber pressure vessels? I don't know how much they weigh but I know they can regulate them for 10,000 psi. Wouldn't it just be a matter of building a large enough carbon fiber tank? or are these tanks still too heavy.

I know Carbon Fiber tanks don't hold up under extreme cold, it was one of the failings of the X-33.

But you are probably right as far as pressurized gas. Most likely they are very heavy, rubber and fiberglass coated Carbon Fiber tanks.

However technology is always improving. (usually )

Edit: Oh and to answer your question, assuming such a tank and pressurized fuel system would work, it would be "Narrow mindedness, Short sightedness, and possibably Arrogance" Kinda like the reason NASA lost two shuttles and probably the same reason they went with a shuttle in the first place, rather than something else.

sounds like carbon nanotubes to me, but there's no good reason why they aren't acceptable. whoever said they won't be commercially available till 2030, you are way too pessemistic. it would be expensive, but you could build such a tank now.